MC3410 Datasheet, PDF (30/75 Pages) NXP Semiconductors – 10-Bit high-speed multiplying D/A converter

MC3410 3-Axis Accelerometer
Datasheet
9.3 FRONT/BACK EVENTS
The front/back detection compares ZOUT with a low g value, ranging from 0.174g to 0.547g,
with the offset from 0.174g specified by the FB_Z_TH: Front/Back Z Axis Threshold Register.
This equates to a range of approximately 55 degrees.
The BAFR bit-field is updated in the TILT: Status Register according to the front/back
orientation sensed by the device. Additional hysteresis can be added to front/back detection by
increasing the front/back Z axis threshold value located in the FB_Z_TH: Front/Back Z Axis
Threshold Register.
When the front/back orientation of the device is in the deadband region, BAFR bit-field will
report the orientation as “unknown”. The default settings (0x00) equate to a range of
approximately 25 degrees where the sensor will report BAFR = FRONT (or BACK). The
maximum settings (0xFF) equate to about a 80 degree range. See Figure 12 and Figure 13.
BAFR =
FRONT +Z
BAFR =
25.0° _UNKNOWN
BAFR =
BACK
-Z
BAFR =
UNKNOWN ^25.0°
FB_Z_TH = 0x00 == 25º
(default, approx.)
Figure 12. Default Setting of FB_Z_TH for BAFR
Readings
BAFR =
FRONT
+Z
BAFR =
80.0° _UNKNOWN
BAFR =
UNKNOWN 80.0°
-Z
BAFR =
BACK
FB_Z_TH = 0xFF == 80º
(maximum, approx.)
Figure 13. Maximum setting of FB_Z_TH for
BAFR Readings
The bit settings for the BAFR bit-field are shown in Table 17. Table 18 shows the front/back
orientation evaluation criteria. Some example threshold values and the corresponding trip
angles are shown in Table 19. All values are approximate and not tested in production.
mCube Proprietary.
APS-048-0010v2.2
© 2014 mCube Inc. All rights reserved.
30 / 75